Outdoor lighting assemblies are well known in the art and can be found in areas requiring overhead lighting such as parking lots, parks, public walkways, and outdoor shopping areas. Outdoor luminaries typically provide light from above, positioned on buildings, poles, masts or other means of support. Design of such overhead lighting should provide easy access for repair and replacement and be aesthetically pleasing while providing the necessary illumination.
Outdoor luminaries typically include a housing or base, an electrical system, and an optical assembly. The housing is usually exposed to the environment and encloses the electrical circuitry, and thus must be capable of protecting the electrical system from moisture and debris. The optical assembly contains a lamp for producing the light and a reflector that directs the light in a predetermined direction. Using different reflector configurations, luminaries are capable of different light distribution patterns such as symmetrical and asymmetrical. These light distribution patterns can be especially suited for roadway, parking and area applications. Lights that provide greater illumination for a given power input are obviously favored, and higher illumination outputs can reduce the number of required lights by increasing the spacing between lights. Depending on the height of the lighting fixture, the beam or area of illumination can be varied to adjust the primary lighting area. In every application, however, greater illumination can offset costs by reducing the number of lights and the wattage of the lights for a given illumination.
The primary emphasis of such lighting is the reflector, which takes many forms and arrangements. Reflectors can be manufactured from metals such as aluminum or polished steel, and can be painted, plated or applied with a chemical surface treatment to brighten the reflective surface. Other techniques for preparing a reflective surface include vacuum deposition or metalizing, and chemical or vapor deposition. These techniques apply a thin layer of metal or other reflective material on the surface of the reflector. There are also prismatic internal reflection glass and plastic reflectors that use the index of refraction to control the reflectance of light and redirect it into a distribution of light. Some glass reflectors are known to use a metal cover spun around the exterior to eliminate uplight, radiated by the large rounded portion of their prism peaks and roots, and the cover is used as a means of glare control and to maintain a clean exterior internal reflection surface.
U.S. Pat. No. 6,726,345 to Arumugusaamy et at. discloses an open type luminaire lens including non-circular reflective lens having a metalized exterior surface and a prism section, the non-circular reflective lens having a shape generally defined by the combination of two parabolas, the prism section including an array of external reflecting prisms of varying predetermined shapes and varying predetermined sizes for use in providing a desired light distribution. This disclosure proposes an aluminum coating directly deposited on an outer section of an elliptical lens.
U.S. Pat. No. 6,123,436 to Hough et al. discloses a reflector with an input aperture positioned near a point of minimum focus and has an output aperture that is larger than the input aperture. The surface is shaped to decrease the angles of incident light rays from the reflector so that an emerging light beam is bounded by a cone the angle of which is less than or equal to the acceptance cone of a projection lens.
U.S. Pat. No. 6,698,908 to Sitzema Jr. et al. discloses an improved optical assembly that includes a reflector device and a reflector collar for enhanced directional illumination control. The reflector/refractor has a predefined shape and has a plurality of prisms on an exterior body surface for reflecting and refracting light. The predetermined contour and the plurality of reflector impressions provide directional illumination control.
U.S. Pat. No. 6,494,596 to Burroughs discloses a reflector for a lighting fixture comprising a substantially bell shaped reflector wall with top and bottom openings and a substantially parabolic cross-section. The reflector wall includes an inner surface having a first top portion that is textured for diffusing light rays from the light source of the fixture, and a second bottom portion that has a smooth surface allowing the light rays to pass through the reflector. The reflector wall also has an outer surface with a plurality of curvilinear prisms for reflecting the light rays.